This invention relates to a method of concurrently promoting general oral hygiene, treating periodontal diseases such as gingivitis and periodontitis, killing oral microbes including cavity-causing bacteria, reducing oral biofilms, increasing blood flow in oral tissues, increasing salivation, promoting gingival tissue regeneration, fostering osteogenesis in the boney structures of the teeth, mouth and related areas, treating systemic diseases associated with oral bacteria, and treating other periodontal and oral maladies through the non-invasive application of weak direct current electricity to the surfaces in the oral cavity, and it also relates to an apparatus suitable for providing direct current electricity for these therapeutic, prophylactic, and regenerative effects.
Periodontal disease has been identified as a risk factor for various systemic diseases by both dentists and physicians. Included in these diseases are cardiovascular disease, adverse pregnancy outcomes, and diabetes with newfound evidence supporting its association with pancreatic diseases and arthritis. While many of the studies establish correlation between the presence of periodontal disease and these systemic conditions, causation, with most of these conditions, is still a subject of ongoing research. A few of the biological mechanisms which have been proposed as to how oral bacteria stemming from periodontal disease can cause systemic disease are as followed:
1. Direct effect of oral infections: Oral microbes and their byproducts can gain systemic access via the circulatory system through traveling through compromised tissue and inflamed periodontium in the oral cavity. In gaining systemic access, oral microbes have the potential to directly influence subclinical mediators of various systemic diseases.
2. Inflammation: People with periodontal disease have elevated levels of systemic inflammatory markers due to the burden of increased levels of oral bacteria. Treatment for periodontal disease has been reported to decrease systemic inflammation levels.
3. Cross-reactivity: The progression of systemic diseases can be accelerated by the immune response to bacterial heat-shock proteins creating antibodies that cross-react with innate heat shock proteins expressed on cells of the damaged tissues.
Cardiovascular Disease
Studies investigating the potential association between periodontal disease and cardiovascular diseases, including atherosclerosis, coronary heart disease, and stroke have found a significant positive correlation between poor oral health and the prevalence of cardiovascular disease. While both diseases share several common risk factors, recent studies suggest that periodontitis may precede and therefore contribute to atherosclerotic complications. In fact, meta-analyses show that subjects suffering from periodontitis experience an increased risk for developing cardiovascular diseases.
While it has not been definitively shown if these bacteria initiate atherosclerosis or rather invade an already compromised artery, antibodies to periodontal bacteria, including Fuseobacterium nucleatum and Streptococcus oralis, have been found in blood serum and are associated with an increased risk of coronary heart disease. A mouse study found that intravenous inoculation with Porphyromonas gingivalis accelerated atherosclerotic development. Further, following oral inoculation, P. gingivalis DNA was found in the aortic tissue of those infected mice that showed observable signs of accelerated early atherosclerosis. Another study has named F. nucleatum as a synergistic agent with P. gingivalis. F. nucleatum enhances the ability of P. gingivalis to invade host cells due to a coaggregating effect between the two organisms. This is significant as bacteria within the atheroma may lead to the development of atherosclerotic plaque. The evidence thus far supports the idea that periodontitis leads to systemic exposure to oral bacteria which serves as a potential source of systemic inflammatory mediators, cytokines produced in the infected periodontal tissues, capable of initiating or worsening atherosclerosis and coronary heart disease when they enter into the blood stream. Clinical studies on periodontal disease have also revealed a positive association with coronary disease and emphasis is now being placed on understanding the exact relation between periodontal disease and atherosclerosis.
Pre-Term Birth
Fusobaceterium nucleatum, one of the most prevalent species of bacteria found in amniotic fluid and placental infections that cause preterm birth, is also often named the sole infectious agent in preterm labor with intact fetal membranes. F. nucleatum is also highly associated with various types of periodontal disease. During periodontal infection, when the oral mucosa is injured and inflamed and the quantities of periodontal pathogens increase dramatically, transient levels of bacteria can appear in the blood leading to selective colonization of undesired sites. One study demonstrated that pregnant mice injected hematogenously with F. nucleatum isolated from either amniotic fluid infection or an oral source resulted in fetal death.
Recently, a human stillbirth case was analyzed and it was found that the F. nucleatum did indeed originate from the mother's oral cavity, a fact that had not yet been proven. It is likely that the F. nucleatum translocated from the mother's mouth via the blood stream where it was then able to cross the endothelium to proliferate and colonize within the fetal membranes, amniotic fluid and fetus whereupon its presence lead to fetal demise. In a mouse model, hematogenous injection of F. nucleatum into pregnant mice resulted in specific bacterial colonization in the placenta causing localized inflammation. F. nucleatum was completely cleared from the maternal circulation after 24 hours of injection. However, once colonized in the immune privileged placenta, the bacteria proliferated quickly and caused fetal death within 3 days. Chronic periodontal disease could mediate infection through the translocation of periodontal bacteria/inflammatory markers to the fetoplacental unit.
Diabetes
Diabetes mellitus is an endocrine disease that stems from genetic, environmental and behavioral risk factors. For the past several decades, diabetes has been considered a modifying factor for periodontal disease with recent years suggesting a bidirectional relationship between the two. Further, presence of periodontal disease has been implicated as a risk for diabetic complications, namely poor glycemic control. Recent longitudinal and systemic studies have seen periodontal disease correlated to higher risks of death from ischemic heart disease, diabetic nephropathy, end-stage renal disease and increased insulin resistance compared to patients with mild or no periodontal disease. In type II diabetes, insulin resistance is linked to the actions of pro-inflammatory cytokines. It is believed that periodontal disease leads to a significantly higher amount of these serum markers of inflammation, thus conferring insulin resistance. A human study examining the bacterial content of adults with and without type II diabetes found diabetic patients had significantly more severe periodontitis and higher levels of many oral bacteria, including Streptococcus oralis. 
Pyogenic Liver Abscess
F. nucleatum has recently been implicated in pyogenic liver abscess (PLA). Normally caused by biliary tract pathology, diverticular disease and bowel malignancy, atrophic gastritis and cryptogenic liver disease, PLA caused by F. nucleatum is very rare with Escherichia coli, Klebsiella and Enterobacter being the most commonly isolated microorganisms in the drained abscesses. F. nucleatum was found in the liver abscess with no other infectious source being found, except for a dental extraction. It is hypothesized that due to the coaggregation properties of F. nucleatum, it is able to transport and breach the mucosa of the colon and lead to bacteremia which results in hepatic abscess.
Osteomyelitis
Osteomyelitis is a bone infection caused by bacteria, fungi or other germs. Commonly, bacteria spreads to the bone from infected skin, muscles or tendons and often time occur under a skin sore. The infection can also start in another part of the body and spread hematogenously. Occasionally Fusobacterium species have been isolated from bone/joint infections in the head and neck area and were associated with chronic periodontitis. A recent study has reported a case of osteomyelitis caused by F. nucleatum in conjunction with muscle abscess. The patient had no known predisposing factors and had no other infection sources except a history of periodontal disease. It is believed that due to the patient's poor oral hygiene, F. nucleatum bacteremia may have developed and lead to a hematogenous osteomyelitis of the lower leg.
Arthritis
Numerous clinical studies have suggested a potential association between rheumatoid arthritis (RA) and periodontal disease as several oral bacteria species, such as P. gingivalis and Prevotella intermedia, have been isolated from the synovial fluid of patients. Periodontal disease is thought to allow bacteria to penetrate through the permeable pocket epithelial in the oral cavity to reach the underlying gingival connection tissue. From there, it may be transported out into the bloodstream with the ability to colonize elsewhere within the body. The oral bacteria found in the synovial fluid of patients suffering from RA has been attributed to synovial inflammation favorably trapping oral bacteria DNA, which suggests periodontal disease may have a perpetuating effect on joint diseases. Therefore, periodontitis may in fact be a factor leading to the autoimmune inflammatory responses characteristic of RA. Patients suffering from RA may also be at a higher risk of developing periodontal disease thus suggesting a bidirectional relationship between the two conditions. One particular study examined the presence of bacterial DNA in the synovial fluids of native and failed prosthetic joints of patients suffering from arthritis. Out of the 5 patients where bacterial DNA was found, F. nucleatum was detected in 4 of these 5 patients. This suggests that this bacterium can translocate from the oral cavity to the synovial fluid, as F. nucleatum was also found in the patient's plaque sample.
Oral Biofilm
Periodontitis, gingivitis, and caries are infectious diseases of the oral cavity in which oral biofilm plays a causative role. Biofilm formation is also involved in the pathogenesis of dental implant failures such as peri-implantitis, denture stomatitis, and oral yeast infections such as candidiasis. Oral biofilms begin with dental pellicle formation on the teeth. This pellicle is composed of salivary proteins that coat the exposed surfaces of the teeth, primarily the supra-gingival ones, to which the planktonic bacteria begin to adhere. The aerobic bacteria, including gram-positive cocci, such as S. oralis, are the early colonizers that begin forming the initial biofilm colony, primarily through cellular division of the adherent bacteria.
Once the initial colony has been established, other co-aggregating bacteria species, such as F. nucleatum, P. gingivalis, and other gram-negative, anaerobic bacteria attach to the previously formed colonies. As these colonies mature, they grow to cover the sub-gingival surfaces of the teeth and begin to induce inflammation in the periodontium.